The present invention relates generally to phase-change materials and relates more particularly to a novel gel comprising a phase-change material, to a method of preparing the gel, and to a thermal exchange implement comprising the gel.
It is often desirable to store and/or to transport temperature-sensitive materials, examples of such temperature-sensitive materials including, but not being limited to, pharmaceuticals, biological samples, foods, and beverages. Packaging systems for storing and/or transporting such materials typically include some means for maintaining the temperature-sensitive materials within a desired temperature range. In many instances, the means for maintaining the temperature-sensitive material within a desired temperature range includes positioning a phase-change material within the storage system in proximity to the temperature-sensitive material. Typically, the phase-change material is selected such that it has a phase change temperature that is within the desired temperature range for the temperature-sensitive material in question. A common phase-change material is water, which is typically thickened or incorporated into some form of a gel for the above-described type of application. Other common phase-change materials include organic compounds, such as n-alkanes (e.g., n-tetradecane, n-hexadecane, and n-octadecane), fatty acid esters (e.g., methyl esters, such as lauric acid methyl ester (also known as methyl laurate) and myristic acid methyl ester (also known as methyl myristate)), fatty alcohols (e.g., decyl alcohol (also known as 1-decanol) and dodecyl alcohol (also known as 1-dodecanol)), and fatty acids (e.g., ricinoleic acid and caprylic acid).
Because phase change materials are designed to be changeable to or from a fluid state, such phase change materials are typically encased within some form of closed container. An example of one common type of closed container is a flexible pouch, and an example of another common type of closed container is a rigid bottle.
One problem that has been encountered, particularly with organic phase-change materials like n-tetradecane is that, because such phase-change materials have very low surface tension, if there is a defect, such as a hole, in the container holding the phase-change material, the phase-change material tends to pass very easily through the defect and subsequently flows near or onto the temperature-sensitive material. As can readily be appreciated, the passage of the phase-change material through such a defect is undesirable. Moreover, in those instances where the container or portions thereof are permeable to the phase-change material (such as where the phase-change material is n-tetradecane and the container for the phase-change material is a polyethylene bottle or a pouch having polyethylene seals), the phase-change material has a tendency, over time, to permeate through the container. Consequently, the phase-change material may “leak” from the container even in the absence of a defect in the container.
Documents of interest may include the following, all of which are incorporated herein by reference: U.S. Pat. No. 7,964,664 B2, inventor Pearce, issued Jun. 21, 2011; U.S. Pat. No. 7,919,163 B2, inventor Romero, issued Apr. 5, 2011; U.S. Pat. No. 7,714,081 B2, inventors Sera et al., issued May 11, 2010; U.S. Pat. No. 7,625,967 B2, inventor St. Clair, issued Dec. 1, 2009; U.S. Pat. No. 7,320,770 B2, inventors Chomard et al., issued Jan. 22, 2008; U.S. Pat. No. 7,294,374 B2, inventor Romero, issued Nov. 13, 2007; U.S. Pat. No. 7,105,104 B2, inventors Chomard et al., issued Sep. 12, 2006; U.S. Pat. No. 6,574,971 B2, inventor Suppes, issued Jun. 10, 2003; U.S. Pat. No. 6,340,467 B1, inventor Morrison, issued Jan. 22, 2002; U.S. Pat. No. 5,994,450; inventor Pearce, issued Nov. 30, 1999; U.S. Pat. No. 5,718,835, inventors Momose et al., issued Feb. 17, 1998; U.S. Patent No. 5,508,334, inventor Chen, issued Apr. 16, 1996; U.S. Pat. No. 5,390,791, inventor Yeager, issued Feb. 21, 1995; U.S. Pat. No. 4,797,160, inventor Salyer, issued Jan. 10, 1989; U.S. Pat. No. RE 34,880, inventor Salyer, issued Mar. 21, 1995; U.S. Patent Application Publication No. US 2011/0281485 A1, inventors Rolland et al., published Nov. 17, 2011; U.S. Patent Application Publication No. US 2011/0248208 A1, inventors Rolland et al., published Oct. 13, 2011; PCT International Publication No. WO 2007/040395 A1, published Apr. 12, 2007; PCT International Publication No. WO 03/057795 A1, published Jul. 17, 2003; European Patent Application Publication No. EP 2,261,297 A2, published Dec. 15, 2010; and European Patent Application Publication No. EP 1,838,802 A2, published Oct. 3, 2007.